There are well established techniques for carrying out endoluminal treatments and diagnoses on a patient. A diagnosis may, for example, involve injection of contrast material and saline solution. A treatment may, for example, involve insertion and deployment of implants or prostheses for carrying out surgical procedures. It may also or in the alternative involve insertion, use and removal of catheters or tools, such as angioplasty or moulding balloons. A treatment may also involve injection of contrast material, saline solution, administration of medicaments and so on. The treatments and diagnoses can be effected within a patient's vascular system, such as arteries or veins. They can also be carried out within other bodily tubes which carry pressurized fluids, examples being the bilary tree and urological system, as well as within other organs such as the cerebral ventricles and so on.
Endoluminal deployment or treatment devices typically include an elongate catheter assembly having an outer sheath which is inserted into the vasculature of the patient from a remote access point up to the deployment or treatment site. For example, for treatment in the aorta, the catheter assembly may be introduced from the femoral artery and fed through the patient's arteries until the distal end of the assembly is located at the position in the aorta at which the treatment is to be carried out. The outer sheath may be used for the passage and retention of elongate deployment elements, for instance catheters or pusher rods, as well as a medical device to be implanted into the patient. The sheath may also be used for carrying tools, catheters for administering medicaments and so on.
In the course of such treatments or endoluminal diagnosis it is important to ensure that the patient does not suffer unnecessary fluid loss through the sheath. For this purpose, it is known to provide at the proximal end of the introducer one or more haemostatic valves in series to close off leakage through the outer sheath. All other catheter based components which have the ability to allow fluid loss therethrough also require some form of sealing or valving.
Haemostatic valve assemblies must allow sliding movement of a variety of different delivery or treatment elements through the valve assembly, as thus through the sheath, while at the same time keeping a seal as such elements pass through or are located in the valve assembly. They must also seal when there is no element in the assembly, that is when the sheath is empty. This requirement generally presents a compromise in terms of sealing efficiency and friction imparted upon any device inserted into the valve assembly. For this reason, some valves provide manual opening and closing of the valve. This, however, involves at least one additional step in the medical procedure and can also lead to the valve failing to provide a seal when in the open configuration, therefore requiring additional valving to avoid unnecessary bodily fluid loss during operation of the valve.
Examples of earlier valves can be found, for instance, in U.S. Pat. Nos. 4,673,393, 5,176,652, US-A-2005/017,479, U.S. Pat. Nos. 5,391,154 and 5,653,697.